Technical Field
The present disclosure relates to an organic light emitting display device and a method of manufacturing the same, and more particularly, to an active matrix (AM) organic light emitting display device and a method of manufacturing the same.
Discussion of the Related Art
Flat panel display devices, which are light and thin, are being actively developed. Representative examples of the flat panel display devices include liquid crystal display (LCD) devices and organic light emitting display devices.
The organic light emitting display devices do not use a separate light source such as a backlight applied to the LCD devices, and thus are thinner, have lower power consumption, and good color reproducibility. Accordingly, the organic light emitting display devices provide a relatively sharper image.
In an active matrix organic light emitting display device that is a type of the organic light emitting display device, a pixel is independently driven, and includes three sub-pixels of red, green, and blue.
Each of the three sub-pixels is defined by intersection between a gate line and a data line, and is independently driven by a driving circuit including a separate thin film transistor (TFT).
Each sub-pixel includes an organic light emitting diode (OLED) which is driven by the driving circuit. The OLED includes a pixel electrode, a common electrode, and an organic emission layer formed between two the electrodes. Foreign materials, such as a particle having a diameter greater than a thickness of the pixel electrode, the common electrode, or the organic emission layer, can occur in a process of forming the OLED.
The pixel electrode may be patterned and formed by a photolithography process. After the pixel electrode is formed, the foreign materials can remain.
There is a high possibility that the foreign materials occur in a process of forming thin layers which are formed on a substrate in common. Representative examples of the thin layers, which are formed on the substrate in common, include the organic emission layer and the common electrode.
In particular, the organic emission layer may be formed by a vacuum deposition process using a shadow mask, a laser transfer process, a thermal transfer process, or a screen printing process. Residual materials can remain after a process. Also, in a top emission type organic light emitting display device, light is output through the common electrode, and a luminance of a central portion of a screen can be reduced due to an increase in a resistance. Therefore, an auxiliary electrode connected to the common electrode may be formed in plurality at the central portion of the screen, for preventing luminance from being reduced due to an increase in a resistance of the central portion of the screen.
A metal oxide layer having a large step coverage may be used for connecting the common electrode to the auxiliary electrode. In this case, the metal oxide layer penetrates into a gap between foreign materials, and for this reason, a possibility that short circuit between the pixel electrode and the common electrode can more increase.
FIG. 1 is a cross-sectional view illustrating an organic light emitting display device in which a defect occurs due to a foreign material. In FIG. 1, the foreign material is illustrated as a particle P.
Referring to FIG. 1, the particle P can occur in a process of forming a pixel electrode 120, an organic emission layer 150, and a common electrode 160 which are formed on a substrate 110. When a diameter of the particle P is greater than a thickness of each of the pixel electrode 120, the organic emission layer 150, and the common electrode 160, the pixel electrode 120 is connected to the common electrode 160, causing short circuit. Here, the common electrode 160 may include a metal layer 161 and a conductive organic layer 162. In FIG. 1, reference numeral 121 refers to an auxiliary electrode, reference numeral 130 refers to a bank layer, and reference numeral 140 refers to a partition layer.
When short circuit occurs between the pixel electrode 120 and the common electrode 160, a current does not flow in the organic emission layer 150, and for this reason, a whole pixel cannot emit light. Therefore, a pixel in which short circuit occurs between the pixel electrode 120 and the common electrode 160 may be a defective pixel which cannot emit light.